This is the thing that doesn't even allow light to pass...what is it?

Black Hole

Explanation:

A black hole is an area of such immense gravity that nothing—not even light—can escape from it. Black holes form at the end of some stars' lives. The energy that held the star together disappears and it collapses in on itself producing a magnificent explosion.

Distance covered, s = 8ft - 4ft = 4 ftinitial velocity, u = 34 ft/sthe acrobat is moving upwards and therefore, a = -g = -9.81 m/s^2 = 32.19 ft/s^2applying equation of motion; s = ut -1/2gt^2then,4 = 34t -1/2*32.19t^24 = 34t - 16.095t^2rearranging; -16.095t^2 + 34t - 4 = 0solving the quadratic equation; t = {-34 +/- sqrt [34^2 - 4(-16.)]}/2(-16.095) = 1.06 +/- 0.93 = 0.13 or 1.99the acrobat will take 0.13 seconds to be at 8 ft above the ground. additionally, once at the maximum height, the acrobat will move down and be at the same spot (that is height) after 1.99 seconds moving down.

D=m/v m=d*vd=densitym=massv=volumed(ether)=0.71 gr/cm³=0.71 gr/ mlv=130 mlm=d*vm=0.71 gr/ml*(130 ml)=92.3 gm=92.3 g